Daniel E. Pilarczyk, an Ohio-born Polish American, was named yesterday by Pope John Paul II as archbishop of Cincinnati, succeeding Archbishop Joseph L. Bernardin.

Pilarczyk, 48, an auxiliary bishop in Cincinnati since 1974, has been apostolic administrator, or official caretaker, of the 19 southern Ohio counties of the archdiocese since Bernardin became archbishop of Chicago last August.

In this position, he told a news conference yesterday, he had been building a file for Bernardin's successor. "I'm in the position to know literally what has to be done this afternoon," he said. "I think I'm ready to go."

Pilarczyk, who has played increasingly important roles in the National Conference of Catholic Bishops as well as in his home diocese, has been viewed as a likely successor to Bernardin, but there was also speculation that the post might go to Bishop James W. Malone of Youngstown.

At 62, and 22 years a bishop, the more seasoned Malone was the choice of some for archbishop because, as current vice-president of the bishop's conference, he is expected to become president of the group when Archbishop John R. Roach completes his term next year. In the past, that post has always gone to the head of one of the American church's 32 archdioceses.

Although only bishop for the past eight years, Pilarczyk has served nationally on some of the key committees of the hierarchy, including the committees on doctrine and education. He is chairman of the education committee.

Washington Archbishop James A. Hickey, who chairs the bishops' doctrine committee, characterized Pilarczyk as "a very competent theologian who is emminently practical . . . a very hard worker who get's his homework done. He is much prized as a committee member."

A native of Dayton, Pilarczyk was graduated from St. Gregory's Seminary in Cincinnati and has degrees from Xavier University and the Pontifical Urban University in Rome, where he was ordained in the priesthood, Dec. 20, 1959.

He began teaching in 1963 at St. Gregory's, which has sinced been merged with another Ohio seminary. Five years later he was named rector, charged with implementing the revolutionary changes of the Second Vatican Council in the training of priests.

When the seminary lacked a qualified instructor in the classics, Pilarczyk completed a doctorate in that field from the University of Cincinnati, in addition to his theological degrees.

More recently, with the growing influx of Hispanics in the half-million member Cincinnati archdiocese, Pilarczyk enrolled in Spanish courses and made room in his schedule for regular monitoring of Spanish-language broadcasts to improve his accent.

Pilarczyk is one of a growing number of Polish Americans rising to leadership positions in the American church, once dominated by Irish Americans.